Thermal Fault Diagnostics for Different Transformer Insulation Systems

This paper presents a comparative study of DGA results for different insulation systems, including pure insulation oils as mineral insulating oil (MIO), natural ester insulating oil (NEIO), synthetic ester (SE) and oil/paper with thermally upgraded kraft paper (TUK), aramid paper (AP), and hybrid paper (HP). Involvement of paper in thermal faults by examining CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>/CO and other key gas ratios are explored in this paper. The results provide insights into the differences in gas evolution across different insulation materials, contributing to improved transformer diagnostics. Over time, these insulating materials degrade due to thermal and electrical stress, generating gases that can be detected using DGA. Understanding the gas formation behavior in different systems is essential for accurate fault diagnosis. This study aims to compare gas generation in pure oils vs. oil/paper systems, establishing trends for fault classification and identifying indicators of paper degradation.